The present invention relates to a radiation measuring probe for contactless measurement of the surface temperature of an object, independent of the emissivity of the object.
A radiation measuring probe of this type is described by G. Seumel et al in "Bestimmung und Regelung der Temperatur von Metallandern mit einem Strahlungsthermometer" (Temperature Determinatin and Regulation of Metal Bands by Means of a Pyrheliometer) published in Metall, Volume 26, No. 4, April, 1972, pages 342-346. The shield of the probe described by Seumel et al has the shape of a hollow, polished hemisphere having an opening for passage of radiation from an object to a measuring probe. The shield is adapted to be placed over the object to be measured. The hemisphere is equipped with a heating coil and a thermocouple, with the temperature of the hemisphere being adjustable to the temperature indicated by the measuring probe. The temperature of the object being measured corresponds to the temperature at which the temperature indications of the hemisphere and measuring probe coincide. (See Seumel et al, supra, at page 343, FIG. 2 and the associated text.) In the foregoing arrangement, however, the hemisphere requires a relatively large distance between the object and the measuring probe, with the resulting disadvantage that temperatures of less than 200.degree. C. cannot be measured with sufficient accuracy.